Electric annealing apparatus



June '29, 1948. R. l. HAHN ELECTRIC ANNEALING APPARATUS Filed April 16, 1947 2 Sheets-Sheet 1 IN VEN TOR. J M

June 29, 1948. R. l. HAHN 2,444,348

ELECTRIC ANNEALING APPARATUS F iled Apr il 16, 1947 2 Sheets-Sheet 2 sa I Mil/Am iB INVENTOR.

Patented June 29, 1943 ELECTRIC AN NEALING APPARATUS Rea I. Hahn, Rochester, N. Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April 16, 1947, Serial No. 741,767

1 Claim. 1

This invention relates to apparatus for annealing continuously moving lengths of metal rods, tubing, wire and the like, for example, the type of apparatus disclosed in Wirt and Fletcher Patent No. 2,293,873. According to this patent, the material is heated, as it travels, by passing electric current through it to raise its temperature to that required for annealing. In order to connect the material with a source of electric current, the material contacts metal pellets contained in metal, electrode-boxes connected with the current source.

An object of the invention is to provide improved electrical connections between the material and the electrode boxes. This is accomplished by using, instead of metal pellets of roughly spherical shape, short, cylindrical rods of non-abrasive, conducting material similar to that used for commutator brushes. Preferably these rods are made by sintering a mixture of finely divided copper and graphite about in the proportion of 60% copper and 40% graphite. For material such as tubing around inch to inch in diameter, satisfactory results are obtained by using rods inch in diameter and to long. As the material moves axially through the masses of rods contained in the boxes, these rods tend to line up parallel to the moving material and to each other and thus provide line contact of lower resistance than the point contact obtained by the use of roughly spherical pellets.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Figs. 1 and 2 together constitute a front view of apparatus embodying the present invention.

Fig. 3 is a view in the direction of arrow 3 of Fig. 1.

Fig. 4 is a sectional view on line 44 of Figs. 1 and 2.

Fig. 5 is a view in the direction of arrow 5 of Fig. 2.

Fig. 6 is a sectional view on line 66 of Figs. 1 and 2.

Fig. 7 is a, fragmentary front view showing one electrode box with cover and one without cover.

Fig. 8 is a sectional view on line 8-8 of Fig. '7.

Fig. 9 is a sectional view on line 9-9 of Fig. 7.

Fig. 10 is a sectional view on line l0-l0 of Fig. 8.

certain tapped holes.

Fig. 11 is a perspective view of a rod for conducting current to the material being annealed.

Fig. 12 is a sectional view on line l2-l2 of Fig. 1.

Fig. 13 is a sectional View on line l3-|3 of Fig. 12.

Fig. 14 is a diagram of electrical connections and corresponding temperature changes.

The electrode boxes 20 are alike except for Each has a cover 2| provided With a handle 22 and attached to the box by screws 23. The side walls 24 and 25 are notched at 28 to receive a metal coupling-bushing 21 retained by lugs 28 which are integral with the cover 2| and is received by the notches 2h. The coupling-bushing 21 and screws 29 tie the boxes together. As shown in Figs. 1, 2 and 14 the boxes are arranged in two end groups of five boxes each and an intermediate group of seven boxes since the latter group conducts more current than the end groups. As shown in Fig. 9, each bushing 21 spans two wall thickness. In order that the same bushings 21 can be used at a box wall at an end of a group, a spacer 21a is attached to provide the necessary wall thickness. Each box 20 receives a quantity of rods 30 made of good contact material as previously specified. The quantity is such as to fill the box to a level substantially above the material (tubing T for example) as indicated by line L (Fig. '7). As the tubing moves longitudinally as indicated by arrows A (Figs. 11 and 14), the rods 30 tend to align themselves parallel to the tubing as indicated in Fig. 10 so as to provide a line contact with the tubing. The rods above those in contact with the tubing also tend to make line contacts with each other so that fairly good electrical patts are provided between the boxes and the tubing. When the boxes are inverted the rods gravitate to spaces below the bushings 2? so that the tubing can be easily threaded through the boxes.

To provide for inversion of the boxes, they are mounted upon an invertible angle bar 3i and attached thereto by screws 32 and 33 and are insulated therefrom in a manner to be described. At each end of the bar 3 I there is welded a clamp plate 34 to which screws 35 attach a clamp plate 36 with a short, tubular shaft 31 between. The two shafts 31 and all of the bushings 21 attached to the boxes are in alignment. The shafts 31 are journaled in bearings 38 carried by brackets 39 attached to a table plate 40 which angles M (Fig. 3) (attach to legs 42 which support the table above the floor. The right end shaft 31 (Fig. 5)

is attached to a worm gear 44 which meshes with a worm '55 attached to a shaft 46 journaled in bearings 41 attached to the right end bracket 39. Shaft do is rotated by a wheel 48 having a crank handle as in order to invert the angle 3| and the boxes 26 when rethreading of the tubing or other material is required.

The tubing passes first through the right end shaf 3? and then through a short, refractory, non-conducting tube 59 (Fig. 6) clamped between two copper half-shells i clamped between a steel block 52 (welded to angle 3|) and a cast bronze block 53 attached by screws 54 to block '52. Tube lit abuts the right end of the right end bushing 2'! of right end group of boxes 20 marked group R in Fig. 2. fhe tubing passes next through group R, boxes 2%) and then through, a refractory tube within a copper tube BI and through a refractory tube E52 within copper half-shells 63 and through a refractory tube 64 within a copper tube Tube 64 abuts the. right end of the rig-ht end bushing 21 of the intermediate group of boxe 20 marked group I. After passing through the box group I, the tubing passes through a refractory tube lo within a cop-per tube H. and through refractory tubes 12, i3 and 14 within copper halfshells i5 and through a refractory tube 1.5 in a copper tube 11. Tube IS abuts the right end of the right end bushing- 2! of the left end group of boxe 2E5 marked group L. The left end bushing 21 of the L boxes abuts another refractory tube 50 (Fig. 6) and the latter abuts the left end. tubular shaft 3?. After passing through the boxes of group L, the tubing passes out through the left end tube Stand left end shaft 3?.

The refractory tubes are made of lava. They can be replaced without disturbing the boxes 20 by the manipulation of clamping levers 80 which cooperate with devices which secure the complete copper tubes E0, 8-5, 19, 1.! or the copper half.- shells 63, '15 in position. For example, as shown in Fig. 12, a steel block 8| is attached by screws 82 to angle 3 and carries pivot rods 83 and 84.. Rod 83 provides a pivot for a. cast bronze block 85 which is held in the position. shown to secure the copper half-shells due. tothe operation of links 236 connecting the pin 84 withapin 81passing eccentrically through the hub 88 of lever 80. When lever Bills loca'tedas-shown, its hubwedges against a hardened steel wear piece 89 provided by block 85. Pins 951 in block 85 limit upward movement of links-85. By pushing down. onlever 8!). theclamp block 85 isquickly released sothat the front half-shell I3 can be removed to provide access to the tubes 1-2:, l3, 14'. which arelo cated by screws 92 threaded; through the back half-shell 13. Since tubes 6'0, G4, 10, Hi are locatedat one end only oftubes 6], 65, ll, 11 r spectively, the latter can be complete tube instead of being split.

The manner of making. electrical connections with the boxes of group I is shown in Fig. 8; Bus bars Hi9, Ifll connectedby wire lflil: (Fig. 14) of a current source are clampediagainst. the boxesZO.

with insulating bar H141 between bar. [0| and. the angle 31. The clamping screws 32uareinsulated by bushings. 10.5 and washers 16.. Screws-33, are insulated by bushings Illlrandawashers L08.

Bus bar lHl which connects together, the end groupsR and L is shownbetweeninsulating bars,

.1 Ill and H2. Bars HE, ill and H by brackets H3 which screws i M a tach to angle 3!. Near the ends thereof, bars Hi and H2 are clamped to bar HG b screws H5 and nuts Hi: (Figs. 1, 2 and 7). Each end portion of bar Hi2 together with a conducting bar is attached by screws IE! to the boxes of the end groups. A wire I23 (Fig. 14) connects bar HO with the current source.

The end groups of boxes are clamped against non-conducting plates 1 supported by the horizontal leg of the angle it; by screws insulated from the angle and threaded into the boxes. The screws 33 which secure all of the boxes to the vertical leg of the angle pass through insulating plates I26 located between the vertical leg and the backs of the boxes as shown in Fig. 8.

The distance between the intermediate box group I and the group R is ess than between groups I and L so that the resistance of the mate-- rial (tubing) being annealed will be less between groups R and I than between groups I and L. Consequently th material will conduct more current between groups R and I than between groups I and L. As shown in 1 1-, line a-b represents a relatively rapid increase of material temperature (to 1396 or 1400 for example) Line cd shows less temperature increase (about 200 F. increase, for example). Therefore, as the material passes through the annealer, its temperature increases relatively rapidly during a certain period of time and then increases relatively slowly for a longer period of time. By changing the relative spacing of the box groups, the annealing cycle can be changed to suit the material being treated. If larger material req 'res more current for the annealing operation, more boxes with rods 30 can be added to each group.

Inert or reducing ga for preventing oxidation of the tubing as it is annealed is conducted under pressure from a source, not shown, through a valve I30, hose l3l, manifold piping I32 and branch pipes IE3 to the passageways for the tubing provided by the part 6!, 85, ii, and Tl.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

Apparatus for annealing continuously moving material, such as metal tubing, wire and the like, comprising an electrode support, metal electrodeboxes located in groups on the support and providing; aligned openings therethrough for the passage of the material, material encasing means located between the groups of boxes and providing non-conducting supports for the material as it passes between the boxes, means for connecting the box groups with a current source and means in each box for making electrical connection between the box and the material passing therethrough, said means comprising a quantity of short, cylindrical rods sufficient to submerge the material, said rods being made of non-abrasive, conducting material and being of such size that, due to the motion of the material through them, a substantial portion of them become axially palallel to the material and to each other.

REA I. HAHN.

are retained t 

